Drives and dmg's are mounting okay on my Mac, and I can find them at /Volumes/. However, they aren't appearing in the sidebar in the Finder. What's the best way to start fixing this?
I faced a similar problem today, but the "devices" show/hide solution didn't quite solve it for me.
However, going to the Finder's Preferences > Sidebar > Devices, the box next to "External disks" was neither empty (unselected) nor check-marked (selected), but rather marked with a hyphen (partially selected). After clicking the box next to "External disks" until the check-mark appeared, my mounted image started to show up in Finder.